Deck 27: Eukaryotic Cells: Origins and Diversity

Question 1

Which of the following is found in eukaryotic cells but not prokaryotic cells?

A)dynamic cytoskeleton
B)cell walls
C)anaerobic metabolism
D)nuclear envelope

Answer 1

A, D

Question 2

Phagocytosis provides a means by which heterotrophic protists can take in food particles. In what way do photosynthetic protists reflect phagotrophy?

A)Photosynthetic protists do not reflect phagotrophy, as these cells fix carbon dioxide into sugars and do not require particulate matter as a source of carbon.
B)Phagotrophy is the process by which cyanobacteria were introduced into protistan cells, to become endosymbionts and, eventually, chloroplasts.
C)Evolutionary loss of the ability to take in particles by phagotrophy forced some protists to evolve a capacity for photosynthesis.
D)Phagotrophy introduces carbon dioxide into the cells of photosynthetic algae where it gets reduced to form sugars.

Answer 2

B

Question 3

Which of the following are ways that genetic diversity is promoted in eukaryotes?

A)conjugation
B)sexual reproduction
C)asexual reproduction
D)transduction

Answer 3

B

Question 4

Which one of the following is an advantage of the relatively small size of the prokaryotic genome?

A)It allows for more diverse regulation mechanisms.
B)It allows prokaryotes to reproduce quickly.
C)It allows for increased diversity.
D)It allows for noncoding genetic material.

Question 5

Which one of the following is NOT part of the endomembrane system?

A)nuclear envelope
B)endoplasmic reticulum
C)mitochondria
D)Golgi apparatus

Question 6

Many single-celled eukaryotic organisms have evolved complex life cycles that include sexual reproduction. This means that:

A)genetic material from two haploid cells is combined.
B)diploid cells must undergo mitotic cell division in order to reproduce.
C)haploid cells must undergo meiotic divisions to form gametes.
D)complex mating behavior likely evolved at the same time as sexual reproduction.

Question 7

Eukaryotic cells and bacteria can both gain nutrition by phagocytosis of other cells.

Question 8

Which one of the following enabled eukaryotes to evolve complex life cycles and programs of multicellular development?

A)binary fission
B)complex patterns of gene regulation
C)a dynamic cytoskeleton
D)sexual reproduction

Question 9

Which one of the following CORRECTLY lists features of eukaryotic cells that distinguish them from prokaryotic cells?

A)a dynamic cytoskeleton, dynamic system of membranes, relatively limited metabolic capabilities
B)a dynamic cytoskeleton, dynamic system of membranes, flexible, wide-ranging metabolic capabilities
C)a dynamic cytoskeleton that permits cellular movement, the ability to carry out photosynthesis, and the ability to switch from haploid to diploid stages in their life cycle

Question 10

Molecular motors associated with the cytoskeleton allow molecules to move through the cell faster than would be possible by diffusion.

Question 11

The diversity of shapes found in eukaryotic cells is made possible by the:

A)nucleus.
B)mitochondria.
C)cytoskeleton.
D)plasma membrane.

Question 12

Animals inherited a sexual life cycle from their protistan ancestors. In what way have animals modified the life cycle characteristic of most protists?

A)In animals, the haploid cells undergo multiple rounds of mitotic cell division before sexual fusion takes place.
B)In animals, the diploid zygote undergoes multiple rounds of mitotic cell division before sexual fusion takes place.
C)Animals have no haploid phase in their life cycle.
D)Animals do not form zygotes as part of their life cycle.

Question 13

Predation by ingesting other cells first arose in prokaryotic organisms, increasing the complexity of interactions among organisms through their ability to engulf particulate food.

Question 14

Many single-celled eukaryotic organisms have evolved complex life cycles that include sexual reproduction. This means that:

A)at some point, two cells must fuse to become diploid.
B)diploid cells must undergo mitotic cell division in order to reproduce.
C)haploid cells must undergo meiotic divisions to form gametes.
D)complex mating behaviors likely evolved at the same time as sexual reproduction.

Question 15

Which of the following processes introduce genetic diversity and contribute to the creation of daughter cells that are genetically unique from one another and from the parent cell?

A)recombination
B)independent assortment
C)meiotic cell division
D)fusion of gametes
E)All of these choices are correct.

Question 16

A dynamic cytoskeleton enables eukaryotic cells to:

A)move.
B)engulf other cells.
C)change shape.
D)All of these choices are correct.

Question 17

What factors contribute to the high observed diversity of eukaryotic organisms?

A)Their genomes contain diverse regulatory sequences.
B)They reproduce sexually.
C)Their dynamic cytoskeleton and membrane systems can generate cells of widely varying size and shape.
D)All of these choices are correct.

Question 18

Many single-celled eukaryotes that normally exist in a haploid state reproduce asexually by:

A)meiotic cell division.
B)binary fission.
C)mitotic cell division.
D)fusion.

Question 19

Mitotic cell division in unicellular eukaryotes can result in a cell that is:

A)1n.
B)2n.
C)Either 1n or 2n, depending on whether the organism predominantly exists as a haploid cell or a diploid cell.

Question 20

Which one of the following are characteristics of eukaryotic cells but not of prokaryotic cells?

A)relatively large genome, dynamic cytoskeleton, compartmentalized metabolic processes
B)two or more circular chromosomes, dynamic membrane system, compartmentalized metabolic processes
C)linear chromosomes, endomembrane system, nucleus, diverse means of harvesting and utilizing energy under anaerobic conditions
D)two or more linear chromosomes, dynamic membrane system, diverse means of harvesting and utilizing energy under anaerobic conditions

Question 21

All of the membranes of the eukaryotic cell are in dynamic continuity except for membranes in the:

A)mitochondria and chloroplasts.
B)endoplasmic reticulum.
C)Golgi apparatus.
D)nuclear membrane.

Question 22

The majority of prokaryotic DNA is arrayed in:

A)multiple circular chromosomes.
B)a single circular chromosome.
C)a single linear chromosome.
D)multiple linear chromosomes.

Question 23

Unlike the rigid protein framework in bacteria, a eukaryotic cell's _____ can be remodeled quickly, enabling the cell to change its shape.

Question 24

How do eukaryotic cells generate and maintain genetic diversity?

A)through horizontal gene transfer
B)through asexual reproduction
C)by allowing more mutations
D)through sexual reproduction

Question 25

Which one of the following is a key advantage of eukaryotic cells over prokaryotic cells?

A)Eukaryotic cells have a cell membrane, which allows them to ship materials into and out of the cell.
B)Eukaryotic cells have ribosomes, which allow them to make more complex proteins.
C)Eukaryotic cells have a flexible cytoskeleton, which allows them to change shape and gives them the ability to engulf other materials.
D)Eukaryotic cells have a rigid cytoskeleton, which allows them to withstand greater stress.
E)None of the answer options is correct.

Question 26

Energy metabolism is localized in the _____ for animal cells and in the _____ for plant cells.

A)mitochondria; mitochondria
B)mitochondria; chloroplasts
C)mitochondria; mitochrondria and chloroplasts

Question 27

Why do some single-celled eukaryotes occur primarily as haploid cells, whereas others occur primarily as diploid cells?

A)Only the eukaryotes that reproduce sexually will occur as diploid cells.
B)Only the eukaryotes that reproduce sexually will occur as haploid cells.
C)Only the eukaryotes that reproduce asexually will occur as diploid cells.
D)Only the eukaryotes that reproduce asexually will occur as haploid cells.
E)None of the answer options is correct.

Question 28

Which of the following organelles contain DNA?

A)the nucleus
B)the ribosome
C)mitochondria
D)chloroplasts

Question 29

What allows multicellular eukaryotic cells to generate multiple, interacting cell types during development?

A)a dynamic cytoskeleton
B)membrane systems
C)gene regulation
D)the ability to perform photosynthesis

Question 30

Eukaryotes have the ability to take in nutrients by phagocytosis, whereas prokaryotes do not. Which of the following explains an advantage this ability brings to eukaryotes?

A)Eukaryotes are able to get bigger because they can now ingest larger materials.
B)Phagocytosis provides eukaryotes with a way of obtaining more DNA for their genome, which allows them to become more complex.
C)Phagocytosis provides eukaryotes with a way of obtaining more RNA for translation, which allows them to become more complex.
D)Eukaryotes are able to exploit complex materials, including other cells, for food that prokaryotes cannot.
E)None of the answer options is correct.

Question 31

Sexual reproduction gave rise to the complex life cycles seen in eukaryotic organisms.

Question 32

Selection favors prokaryotic organisms that maintain smaller genomes over prokaryotic organisms with larger genomes.

Question 33

You are in a lab studying a newly discovered cell type. You observe a rigid cytoskeleton in this cell, along with a nucleus and a compartmentalized interior. How would you classify this cell?

A)as an advanced prokaryotic cell, because it has a rigid cytoskeleton
B)as a primitive prokaryotic cell
C)as a possible transitional cell from prokaryotic to eukaryotic
D)as a eukaryotic cell that has to be heterotrophic
E)None of the answer options is correct.

Question 34

Many plants and animals can reproduce asexually.

Question 35

Which one of the following structures has the GREATEST membrane stability?

A)cell membrane
B)nuclear membrane
C)rough endoplasmic reticulum
D)Golgi apparatus
E)mitochondria

Question 36

In animals, the egg and sperm cells are:

A)polyploid.
B)diploid.
C)haploid.
D)None of the answer options is correct.

Question 37

Eukaryotes have more ways to obtain energy than prokaryotes.

Question 38

You have learned that having linear DNA has consequences, the major one being that the DNA gets shortened every time it replicates, something that does not happen with the circular DNA found in prokaryotes. What, then, is the advantage of having linear DNA?

A)Linear DNA is easier to package than circular DNA.
B)Linear DNA is less susceptible to viruses than circular DNA.
C)Since mitochondria and chloroplasts have circular DNA, nuclear DNA had to be linear.
D)Replication can begin from multiple sites on linear DNA, allowing rapid replication and relieving the evolutionary pressure for a streamlined genome.
E)All of these choices are correct.

Question 39

Which of the following accounts for why eukaryotic cells are typically much larger than prokaryotic cells?

A)Since eukaryotic cells have more DNA, their cell volume has to be larger.
B)A eukaryotic nucleus is so large that the cell has to be bigger to absorb the space needed for other organelles.
C)Reproducing sexually requires the cells to be larger so that everything in the cell can be evenly distributed to the daughter cells.
D)Using molecular motors, eukaryotic cells can transport materials throughout their cytoplasm much faster than prokaryotic cells can, since prokaryotic cells have to rely on simple diffusion.
E)None of the answer options is correct.

Question 40

Sexual fusion brings two haploid cells together to produce a _____ cell.

A)polyploid
B)diploid
C)haploid
D)None of the answer options is correct.

Question 41

Evidence that supports chloroplast origins from photosynthetic bacteria includes:

A)similar organization of photosynthetic membranes.
B)the use of two linked photosystems to capture electrons from water.
C)similarities in the DNA sequence of the chloroplast chromosome and bacterial chromosome.
D)All three of these features provide evidence for the bacterial origin of chloroplasts.

Question 42

Which of the following is NOT a line of evidence supporting the endosymbiotic theory for the origin of chloroplasts?

A)Chloroplasts have a single circular chromosome.
B)Chloroplasts use two linked photosystems for photosynthesis.
C)Chloroplasts use exclusively chlorophyll a and b.
D)Chloroplasts in some algae are surrounded by two membranes.

Question 43

There are two competing theories put forth to explain the origin of eukaryotic cells. Which of the following CORRECTLY states one of these theories?

A)Ancient eukaryotic cells resembling archaeal cells acquired symbiotic bacteria that eventually took up permanent residence to become mitochondria.
B)Two types of prokaryotic cells, one of which was photosynthetic, fused to become the first ancient eukaryotic cell.
C)A symbiotic relationship between a cyanobacteria and an archaeon created the first ancient eukaryotic cell.
D)Ancient eukaryotic cells resembling archaeal cells acquired symbiotic cyanobacteria that eventually took up permanent residence to become chloroplasts.

Question 44

Which of the following statements regarding diatoms is FALSE?

A)Most diatoms are multicellular eukaryotes.
B)Diatoms (normally)exist in a diploid state.
C)Depending on environmental conditions, diatoms can undergo either meiotic or mitotic cell division.
D)Diatoms possess mineralized skeletons.
E)Diatoms can produce haploid gametes.

Question 45

What is the main difference between the two hypotheses for the origin of the eukaryotic cell?

A)One attributes the formation of the endoplasmic reticulum and nuclear envelope to infolding of the plasma membrane.
B)Only one involves the conversion of a proteobacterium to a mitochondria.
C)One hypothesizes that eukaryotic cells evolved from an archaeon rather than a bacterium.
D)One hypothesizes that engulfment of a proteobacterium occurred after formation of the nuclear envelope rather than before.

Question 46

What is the possible significance of the finding that genes related to bacteria and archaea occur in the eukaryotic genome?

A)The ancestor of the modern eukaryotic cell may have been a primitive, mitochondria-free cell with a nucleus.
B)An archaeon may have engulfed a bacterium to form a eukaryotic cell.
C)The presence of genes related to bacteria and archaea is a byproduct of meiosis.
D)These genes may be the result of horizontal gene transfer.

Question 47

Organelles have their own genomes. When chloroplast DNA is sequenced and compared to genomes from members of the cyanobacteria, the sequence is nested within cyanobacteria. This is strong evidence for the hypothesis that:

A)cyanobacteria are descended from chloroplasts.
B)cyanobacteria are so diverse that any organelle genome would nest within the group.
C)photosynthesis evolved only once on the eukaryotic tree.
D)the chloroplast originated as a symbiotic cyanobacterium that became permanently incorporated into its host.

Question 48

Chloroplasts are thought to have originated from a symbiotic relationship between an ancient eukaryotic cell and:

A)an archaeal cell.
B)a cyanobacterium.
C)a proteobacterium.
D)algae.

Question 49

Why do mitochondria and chloroplasts have small genomes?

A)Because their bacterial ancestors did.
B)Because they do not need many genes to function.
C)Because they lack noncoding DNA.
D)Because over time, much of their DNA has migrated to the host cell nucleus.

Question 50

Which of the following explains why photosynthesis is widely but discontinuously distributed throughout the eukaryotic tree?

A)Photosynthesis was acquired early in evolution, but then lost.
B)Photosynthesis was acquired multiple times through endosymbiosis.
C)All eukaryotes are capable of photosynthesis, but it is repressed in some cases.
D)Some eukaryotes evolved photosynthetic pathways separate from chloroplasts.

Question 51

Chloroplasts closely resemble photosynthetic _____.

Question 52

Not all eukaryotes contain a dynamic cytoskeleton-or even a cytoskeleton at all. The smallest eukaryotes actually possess rigid cell walls composed of peptidoglycan, much like bacteria.

Question 53

Which of the following best describes a symbiotic relationship between two organisms?

A)Two organisms live in close, long-term, physical association with each other.
B)Two organisms live in close, physical association with each other where both organisms benefit from the relationship.
C)Two organisms live in close, physical association with each other where both organisms thrive, but one is the primary provider and the other is the primary beneficiary.
D)Two organisms live in close, physical association with each other where one organism benefits to the detriment of the other.

Question 54

Chloroplasts are thought to have evolved from cyanobacteria. Which of the following observations support this hypothesis?

A)They both have similar internal membranes that organize the light reactions of photosynthesis.
B)They both have small circular DNA genomes.
C)They both have cell walls.
D)They both have the capability of movement through flagella.

Question 55

Which of the following is evidence that supports the hypothesis that eukaryotic chloroplasts may have originated from cyanobacteria?

A)Chloroplasts and cyanobacteria have similar DNA sequences for shared genes.
B)Chloroplasts and cyanobacteria both have cell walls.
C)Chloroplasts can leave the cell and function freely on their own.
D)Chloroplasts and cyanobacteria have the same number of genes.

Question 56

Which of the following is responsible for the evolutionary success of eukaryotes?

A)possessing a dynamic cytoskeleton
B)having complex patterns of gene regulation
C)localizing where energy metabolism takes place
D)possessing a dynamic endomembrane system
E)All of these choices are correct.

Question 57

Mitochondria and chloroplasts are thought to have arisen from:

A)endosymbiotic bacteria.
B)parasitic interactions.
C)normal organelle development.
D)None of the answer options is correct.

Question 58

Chloroplasts are thought to have evolved from:

A)algae.
B)autotrophic protists.
C)mitochondria.
D)cyanobacteria.
E)proteobacteria.

Question 59

Chloroplasts have an outer and an inner membrane that separate the stroma and thylakoid membrane from the cytoplasm. What is believed to be the origin of the outer membrane of the chloroplast?

A)It is the remnant of the ancient host cell's plasma membrane following endocytosis of the cyanobacterium.
B)It is a nonfunctional remnant resulting from the amplification of the inner membrane of the chloroplast to increase its surface area.
C)It is an adaptation of the symbiotic cyanobacteria to protect it from fusing with lysosomes present in the cytoplasm of the ancient "host" cell.

Question 60

What data convinced biologists that the photosynthesis in Paulinella chromatophora originated independently of the endosymbiotic events that gave rise to chloroplasts in green algae?

A)Nucleotide sequences of genes in the chloroplasts of Paulinella show that these organelles are most closely related to cyanobacteria different from those from which green algal chloroplasts arose.
B)Paulinella belongs to a different superkingdom from the green algae, and each superkingdom with photosynthetic members arose from a different endosymbiotic event.
C)Green algae have cell walls made of cellulose, but Paulinella does not.
D)Paulinella has a chloroplast that arose by means of a second endosymbiotic event incorporating a photosynthetic eukaryote; the presence of multiple membranes in these chloroplasts supports its independent origin from chloroplasts in green algae.

Question 61

Imagine that a researcher discovers a new type of organelle in single-celled eukaryotes. She suspects this new organelle is the result of endosymbiosis. How could she support this theory?

A)She could use electron microscopy to determine if any structural similarities exist between this new organelle and prokaryotic cells (i.e., like proteobacteria or cyanobacteria).
B)She could determine whether this organelle has both an inner and outer membrane.
C)If this organelle has its own DNA, she could compare its genetic sequence to those of certain prokaryotes.
D)All of these choices are correct.

Question 62

Clorarachniophyte and cryptophyte algae contain three sets of genetic material: the nuclear genome, the chloroplast genome, and a set of genes found in the nucelomorph. What, in terms of the endosymbiotic hypothesis, is represented by the nucleomorph genes?

A)genes introduced by viral infection
B)genes that migrated from the host's nucleus into the symbiont
C)genes that migrated from the chloroplast into the host's genome
D)remnant genes from the nucleus of a eukaryotic algal endosymbiont

Question 63

Among eukaryotes, some multicellular organisms lack both chloroplasts and mitochondria.

Question 64

Why haven't more groups within the archaeplastids developed complex multicellularity?

A)Many of the groups are recently evolved; with more time they will all evolve members with complex multicellularity.
B)Many of the groups are marine, and there are a limited number of marine niches that require complex multicellularity.
C)Evolution is not goal-oriented toward producing an end product with complex multicellularity; each group is successful with its current morphology.
D)Only the most diverse groups have enough species so that complex multicellularity can evolve.

Question 65

A symbiont is an organism that lives in close association with another species.

Question 66

Which of the following is a hypothesis to explain the origin of the modern eukaryotic cell?

A)A cell evolved a nucleus first, then incorporated a proteobacterial cell that became a mitochondrion.
B)A cell evolved a nucleus first, then incorporated a cyanobacterial cell that became a mitochondrion.
C)A cyanobacterial cell became incorporated into an archaeon at the same time that eukaryotes developed.
D)A proteobacterial cell became incorporated into an archaeon at the same time that eukaryotes developed.
E)None of the answer options is correct.

Question 67

The photosynthetic amoeba Paulinella is an example of a second chloroplast endosymbiotic event involving a cyanobacterium.

Question 68

Which of the following is NOT true of protists?

A)They may have cell walls.
B)They may be photosynthetic.
C)They may be prokaryotic.
D)They are usually aerobic, though some are not.
E)Some are unicellular.

Question 69

To which superkingdom do humans belong?

A)Archaeplastida
B)Alveolata
C)Excavata
D)Opisthokonta
E)Rhizaria

Question 70

Chloroplasts originated from endosymbiotic cyanobacteria once and only once.

Question 71

Mitochondria are thought to have evolved from:

A)amoeba.
B)heterotrophic protists.
C)chloroplasts.
D)cyanobacteria.
E)proteobacteria.

Question 72

Most eukaryotic cells contain mitochondria, but a few single-celled eukaryotic organisms found in oxygen-free environments do not. Which of the following observations led biologists to reject the hypothesis that these mitochondria-free eukaryotes evolved BEFORE the endosymbiotic event that established mitochondria in other eukaryotes?

A)All eukaryotes exhibit some sort of energy utilization.
B)Some eukaryotes don't have mitochondria, they have chloroplasts instead.
C)The nuclear genome of these mitochondria-free eukaryotes contains relics of mitochondrial genes.
D)All eukaryotes have remnant chloroplast genes.

Question 73

In eukaryotes that lack mitochondria, what structures are present to generate ATP for cellular use?

A)There are no eukaryotes that lack mitochondria.
B)There are no structures that generate ATP in eukaryotes that lack mitochondria.
C)hydrogenosomes
D)chloroplasts
E)chloroplasts or hydrogenosomes

Question 74

Chloroplasts and mitochondria in eukaryotes are thought to have originated by _____, wherein one organism lives inside another.

A)endosymbiosis
B)parasitism
C)partial symbiosis
D)antagonism
E)phagocytosis

Question 75

The only known eukaryotic-bacterial symbioses are the two that explain the development of the chloroplast and mitochondria.

Question 76

The current theory is that chloroplasts are descendants of symbiotic cyanobacteria that lived within eukaryotic cells. If we look at their respective genomes, however, we see that the cyanobacteria have many more genes than do chloroplasts. Where did these genes go?

A)Restriction enzymes removed them.
B)Endosymbiosis requires a reduction in genetic material in order to be successful.
C)Many of the genes were transported to the nucleus, and others were lost.
D)Nowhere; cyanobacteria and chloroplasts actually have the same number of genes.
E)None of the answer options is correct.

Question 77

How does current theory explain the origin of a nucleus in eukaryotic cells?

A)A prokaryotic cell was engulfed by another cell and became specialized in DNA replication.
B)A prokaryotic cell was engulfed by another cell and became specialized in DNA transcription.
C)A prokaryotic cell was engulfed by another cell and became specialized in translation.
D)While there are some competing theories on the origin of the nucleus, neither theory discussed in the text really explains the origin of the nucleus.
E)None of the answer options is correct.

Question 78

There is no known symbiosis between a heterotrophic host and a photosynthetic partner in mammals.

Question 79

Which is your CLOSEST relative?

A)a slime mold
B)a mushroom
C)an apple tree
D)the malaria parasite

Question 80

The genes in chloroplasts more closely match the genes found in cyanobacteria compared to the genes found in the nuclei of photosynthetic eukaryotes.